U.S. patent application number 12/681997 was filed with the patent office on 2010-08-26 for doctor apparatus and a method for a web forming machine for doctoring a moving surface as well as a blade holder.
This patent application is currently assigned to METSO PAPER, INC.. Invention is credited to Hannu Eerikainen, Reijo Hassinen.
Application Number | 20100215857 12/681997 |
Document ID | / |
Family ID | 38656865 |
Filed Date | 2010-08-26 |
United States Patent
Application |
20100215857 |
Kind Code |
A1 |
Eerikainen; Hannu ; et
al. |
August 26, 2010 |
Doctor Apparatus and a Method for a Web Forming Machine for
Doctoring a Moving Surface as Well as a Blade Holder
Abstract
A doctor apparatus for a web forming machine for doctoring a
moving surface with the doctor apparatus (10) has a blade (16), a
blade holder (14) to which the blade (16) is adapted, a frame
component (12) to which the blade holder (14) is adapted, and a
loading element (23) arranged between the frame component (12) and
the blade holder (14) for loading the blade holder (14) and further
the blade (16). The loading element (23) is tied to both the frame
component (12) and the blade holder (14). The invention also
relates to a blade holder (14) and a method for a web forming
machine for doctoring a moving surface (26).
Inventors: |
Eerikainen; Hannu; (Varkaus,
FI) ; Hassinen; Reijo; (Leppavesi, FI) |
Correspondence
Address: |
STIENNON & STIENNON
612 W. MAIN ST., SUITE 201, P.O. BOX 1667
MADISON
WI
53701-1667
US
|
Assignee: |
METSO PAPER, INC.
Helsinki
FI
|
Family ID: |
38656865 |
Appl. No.: |
12/681997 |
Filed: |
October 3, 2008 |
PCT Filed: |
October 3, 2008 |
PCT NO: |
PCT/FI2008/050548 |
371 Date: |
April 28, 2010 |
Current U.S.
Class: |
427/294 ;
118/256; 118/261 |
Current CPC
Class: |
D21G 3/005 20130101;
D21G 3/00 20130101 |
Class at
Publication: |
427/294 ;
118/261; 118/256 |
International
Class: |
B05C 1/14 20060101
B05C001/14 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 10, 2007 |
FI |
20075718 |
Claims
1-25. (canceled)
26. A doctor apparatus for a web forming machine for doctoring a
moving surface, comprising: a frame component; a blade holder
mounted to the frame; a blade mounted to the blade holder; a
loading element arranged between the frame component and the blade
holder, and tied to both the frame component and the blade holder,
the loading element for loading the blade in the blade holder
against a surface.
27. The doctor apparatus of claim 26, wherein the blade holder is
mounted to the frame by a connection therebetween; wherein the
blade defines a tip, a base, and a plane containing the tip and the
base, and the blade defines a rotation direction which moves the
tip in rotation toward a position occupied by the base; and wherein
the blade and the loading element are arranged on opposite sides of
the connection, and the connection mounts the blade holder for
rotation in the rotation direction.
28. The doctor apparatus of claim 26 wherein the loading element is
a loading hose.
29. The doctor apparatus of claim 28 wherein the loading hose is
connectable to a source of vacuum and when connected to the source
of vacuum the loading hose has a configuration which detaches the
blade from the surface.
30. The doctor apparatus of claim 27 wherein the loading hose
includes a first fastening profile, and a second opposite fastening
profile, wherein the first fastening profile connects the loading
hose to the frame component, and the second fastening profile
connects the loading hose to the blade holder.
31. The doctor apparatus of claim 27 wherein the fastening profiles
protrude from the loading hose.
32. The doctor apparatus of claim 29 wherein the blade holder has
portions defining a first hose groove, and the frame component has
portions defining a second hose groove and wherein the loading hose
is located in the first and second hose grooves, wherein the hose
groove defines a hose diameter line such that the first and second
fastening profiles are on opposite sides of the diameter line
relative to the connection allowing turning between the blade
holder and the frame component.
33. The doctor apparatus of claim 29 wherein an angle (.alpha.) is
defined between the opposite fastening profiles and is between
40.degree.-140.degree..
34. The doctor apparatus of claim 33 wherein the angle (.alpha.) is
between 70.degree.-110.degree..
35. The doctor apparatus of claim 27 wherein the cross section of a
wall forming the loading hose is curved over a portion exceeding
70% or 90% of the wall forming the loading hose.
36. The doctor apparatus of claim 27 wherein the loading hose
includes a first wall portion which is outwardly curved, a second
wall portion which is outwardly curved, and a third wall portion
which is outwardly curved.
37. The doctor apparatus of claim 27 wherein the loading hose is
connected to a source of vacuum and wherein the loading hose has an
inner surface exposed to the source of vacuum, the inner surface
including a first wall portion on the inner surface, a second wall
portion on the inner surface and a third wall portion on the inner
surface, wherein the third wall portion is between the first wall
portion and the second wall portion.
38. The doctor apparatus of claim 37 wherein the first wall portion
and the second wall portion are curved.
39. The doctor apparatus of claim 29 wherein the loading hose
includes a first wall portion, a second wall portion and a third
wall portion and the first and second fastening profiles are
located on either side of the third wall portion.
40. The doctor apparatus of claim 39 wherein the loading hose is a
circuit formed by the first wall portion, the second wall portion,
the third wall portion and a fourth wall portion.
41. The doctor apparatus of claim 27 wherein the cross section of
the loading hose is substantially circular at a selected stage of
loading.
42. A blade holder for a doctor blade, comprising: wherein the
blade holder includes only one loading element groove, said loading
element groove adapted to bidirectional loading.
43. The blade holder of claim 42 having a blade groove to which a
blade is adapted to be attached, with the blade holder having a
connection component that allows turning and fastening the blade
holder to a frame component, wherein the loading element groove is
on an opposite side of the connection component, relative to the
blade groove in a direction parallel with the blade groove.
44. The blade holder of claim 42 wherein the loading element groove
is a hose groove.
45. The blade holder of claim 42 wherein the loading element groove
includes a counter profile and a loading element profile.
46. A method in a web forming machine for doctoring a moving
surface, comprising the step of adjusting a gap between a doctor
blade and a moving surface with a loading element which is tied to
both a frame component and a blade holder to which the doctor blade
is mounted, so that the blade and blade holder are moved with
respect to the frame component by the loading element.
47. The method of claim 46 further comprising the step of: using a
loading hose as the loading element and depressurizing the loading
hose to adjust the gap between the blade and the moving
surface.
48. The method of claim 46 wherein the gap between the blade and
the surface is opened by depressurizing the loading hose.
49. The method of claim 48 wherein the loading hose has a first
wall portion, a second wall portion, and a third wall portion
therebetween, and upon depressurization of the loading hose the
third wall portion remains between the first wall portion and the
second wall portion.
50. The method of claim 48 wherein the gap between the blade and
the surface is closed by overpressurizing the loading hose.
51. A doctor apparatus in a web forming machine for doctoring a
moving surface, comprising: a cylindrical roll mounted in the web
forming machine to rotate about a cylinder axis, the roll having a
cylindrical surface which moves when the cylindrical roll rotates
about the cylinder axis; a frame component, fixedly mounted with
respect to the cylindrical roll axis; a blade holder mounted to the
frame for rotation about a connecting component; a doctor blade
mounted to the blade holder, and extending parallel to the cylinder
axis, and having a blade tip engageable with the cylindrical
surface, the doctor blade in the blade holder being mounted by the
connecting component to the frame component for rotation about a
connecting component axis which is parallel to the cylinder axis
into and out of engagement with the cylindrical surface; a loading
tube arranged between the frame component and the blade holder, and
tied to both the frame component and the blade holder, the loading
tube located opposite the blade tip with the connecting component
therebetween; wherein the loading tube is switchably connected to a
source of pressurized air for expanding the loading tube to cause
rotation of the blade holder and blade about the connecting
component axis to load the blade in the blade holder against the
cylindrical surface, and wherein the loading tube is switchably
connected to a source of vacuum for collapsing the loading tube to
cause rotation of the blade holder and blade about the connecting
component axis to lift the blade in the blade holder away from the
cylindrical surface.
52. The doctor apparatus of claim 51 wherein the loading tube
further comprises a substantially cylindrical loading tube having a
first profile extending from and along the tube, and a second
profile extending from and along the tube spaced apart from the
first profile between 70.degree.-110.degree. about a circumference
defined by the loading tube, and wherein the first profile engages
a complementary counter profile defined by a portion of the frame,
so the first profile is tied to the frame, and the second profile
engages a complementary counter profile defined by portions of the
blade holder so that the second profile is tied to the blade
holder.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application is a U.S. national stage application of
International App. No. PCT/FI2008/050548, filed Oct. 3, 2008, the
disclosure of which is incorporated by reference herein, and claims
priority on Finnish App. No. 20075718, filed Oct. 10, 2007.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH AND DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] The invention relates to a doctor apparatus for a web
forming machine for doctoring a moving surface with the doctor
apparatus including a blade, a blade holder to which the blade is
adapted, a frame component to which the blade holder is adapted,
and a loading element is arranged between the frame component and
the blade holder for loading the blade holder and further the
blade.
[0004] The invention also relates to a blade holder and a method
for a web forming machine for doctoring a moving surface.
[0005] At present, an apparatus for doctoring a moving surface is
known, for example, from publication U.S. Pat. No. 6,942,734. The
apparatus includes a frame component to which a blade holder is
connected. The blade holder, in turn, has a blade connected
thereto. The blade holder is loaded with a loading hose and for the
loading hose, on the other hand, a counter force is provided with
an opening hose. In other words, the opening hose providing the
counter force for the loading hose is used to open the gap between
the blade and a roll surface. There are known several corresponding
apparatuses in which the gap between a blade and a roll surface is
opened by means of an opening hose and closed by means of a loading
hose. However, a common problem with the use of these is that the
design of the opening hose is restricted, which means that the
opening of the gap between the blade and the roll surface is also
restricted. An opening hose and a loading hose also substantially
complicate the removal of the blade holder from the frame
component.
[0006] Publication WO 01/25533 proposes a doctor blade holder and a
method for using a doctor. In this publication, it is proposed that
the counter force for the loading hose is produced with flexible
plates. Plates, however, fatigue in the course of time, whereby the
apparatus fails to function as planned.
SUMMARY OF THE INVENTION
[0007] The object of the invention is to provide a novel doctor
apparatus which can be connected to a web forming machine
economically more advantageously than before. The characteristic
features of this invention are that the loading element is tied to
both the frame component and the blade holder. A further object of
the invention is to provide a novel blade holder which can be
removed and set in place more easily than before. The
characteristic features of this invention are that the blade holder
includes only one loading element groove adapted to bidirectional
loading. A still further object of the invention is to provide a
novel method for a web o forming machine for doctoring a moving
surface. In the method, the blade holder turns to a larger extent
than before. The characteristic features of this invention are that
the gap between the blade and the surface is adjusted with a
loading element which is tied to both the frame component and the
blade holder.
[0008] In the method according to the invention, the gap between a
blade and a surface in a web forming machine is adjusted. A moving
surface is doctored with the blade. A web manufacturing machine
refers to machines intended for manufacturing paper, tissue or
board. A web, in turn, is used to refer to board, tissue and paper
webs. The gap between the blade and the surface is adjusted with a
loading element. Surprisingly, the gap between the blade and the
surface is adjusted with a loading element which is tied to both a
frame component and a blade holder. Locating the loading element in
a new way enables both loading the surface to be doctored and
detaching the blade from the surface to be doctored with the
loading element.
[0009] In an embodiment, a loading hose is used as the loading
element, which is depressurized for adjusting the gap between a
blade and a surface to be doctored. Adjusting the gap between the
blade and the surface to be doctored by depressurizing the loading
hose enables locating the loading hose in a new way. When locating
the loading hose in a new way, it is possible to make the loading
hose, for example, larger than before, which allows opening the gap
between the blade and the surface to a greater extent.
[0010] In a second embodiment, the gap between the blade and the
surface is opened by depressurizing a loading hose. Opening the gap
between the blade and the surface by depressurizing the loading
hose is useful since the gap between the blade and the surface
needs to be open only for short periods of time. Such periods of
time exist in connection with shutdowns and grade changes. In turn,
the time the gap between the blade and the surface remains closed,
i.e. loading the surface with the blade, is long, in which case a
vacuum would be needed for long periods of time in a loading system
implemented with a vacuum. Generating an overpressure is more
economical than generating a vacuum. Opening the gap between the
blade and the surface is thus more advantageous with a vacuum than
loading a roll surface with a vacuum.
[0011] In a third embodiment, a full or an overpressurized loading
hose includes a first wall portion, a second wall portion and a
third wall portion, and when depressurizing the loading hose, the
third wall portion remains between the first wall portion and the
second wall portion. Thus the loading hose becomes a lot smaller
and thereby moves the blade holder tied thereto and the frame
component relative to each other increasingly when the loading hose
is depressurized.
[0012] In a fourth embodiment the gap between the blade and the
surface is closed by overpressurizing a loading hose. In other
words, the same loading hose is used for both opening and closing
the gap between the blade and the surface. When using the same
loading hose for both closing and opening, it is sufficient to have
one loading hose instead of two. Loading hoses and particularly
pressure pipes led to these create high costs, which can be
remarkably reduced when using a single loading hose for opening and
closing the gap between the blade and the surface.
[0013] The invention is described below in detail by making
reference to the drawings, which illustrate some of the embodiments
of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1a shows a doctor apparatus according to prior art.
[0015] FIG. 1b shows another doctor apparatus according to prior
art.
[0016] FIG. 2 shows an embodiment of the doctor apparatus according
to the invention.
[0017] FIG. 3a shows another embodiment of the doctor apparatus
according to the invention with the blade contacting the roll
surface.
[0018] FIG. 3b shows the doctor apparatus of FIG. 3a with the blade
detached from the roll surface.
[0019] FIG. 4 shows the blade holder according to the
invention.
[0020] FIG. 5a shows a doctor apparatus according to prior art in
the closed position.
[0021] FIG. 5b shows the apparatus according to the invention in
the closed position.
[0022] FIG. 5c shows FIGS. 5a and 5b set on top of each other.
[0023] FIG. 6a shows a doctor holder according to prior art in the
neutral position.
[0024] FIG. 6b shows the doctor holder according to the invention
in the neutral position.
[0025] FIG. 6c shows FIGS. 6a and 6b set on top of each other.
[0026] FIG. 7a shows a doctor holder according to prior art in the
open position.
[0027] FIG. 7b shows the doctor holder according to the invention
in the open position.
[0028] FIG. 7c shows FIGS. 7a and 7b set on top of each other.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] FIG. 1a illustrates a doctor apparatus 10' according to
prior art. The doctor apparatus 10' according to prior art includes
a frame component 12, to which a blade holder 14 is connected. A
blade 16 and a presser blade or a pressure plate 18 are in turn
connected to the blade holder 14. The blade holder 14 is loaded
with a loading element 19', more precisely with a loading hose 20',
while an opening hose 22' provides the counter force for the
loading hose 20'. The loading hose 20' is adapted to close the gap
between the blade 16 and a roll surface 26. The opening hose 22',
in turn, is adapted to open the gap 38 between the blade 16 and the
roll surface. The size of the opening hose and the projection
required by the opening hose in the blade holder restrict the
opening of the gap between the blade and the surface. The location
of the opening hose, in turn, restricts the size of the opening
hose. Two separate loading hoses also complicate the removal of the
blade holder from the frame component, due to friction. Each
loading hose also increases attachment of dirt to the doctor
apparatus. Moreover, two separate loading hoses require two
separate pipeworks for leading a vacuum to the loading hoses. Two
separate pipeworks make a significant cost item since a web forming
machine has several doctor apparatuses.
[0030] FIG. 1b shows another doctor apparatus according to prior
art. A loading element 19', more precisely a loading hose 20', is
located between a frame component 12 and a blade holder 14.
[0031] The blade holder consists mainly of plates 21'. The frame
component 12 has a profile 23' for the loading element 19' or more
precisely for the loading hose 20', but the blade holder does not
have a corresponding profile. The operating principle of the doctor
apparatus shown in FIG. 1b is different from that of the one shown
in FIG. 1a. Although the loading force is generated in a
corresponding way with the loading hose 20, the counter force is
generated with flexible plates 21'. Plates, however, fatigue in the
course of time, whereby the entirety will no more function as
desired. Such a doctor apparatus requires space and the movement
allowed for the blade is small. Keeping the loading hose in place
is also a problem.
[0032] FIG. 2 shows the doctor apparatus 10 according to the
invention for a web forming machine for doctoring a moving surface.
The doctor apparatus includes a blade 16, which is adapted to
doctor a moving surface. The blade 16 is adapted in a blade holder
14, which is adapted in a frame component 12. The blade 16 is
supported by a presser plate 18. A loading element 23 is arranged
between the frame component 12 and the blade holder 14 for loading
the blade holder 14 and further the blade 16. In addition, both the
frame component 12 and the blade holder 14 are tied to the loading
element 23 for moving the blade holder and further the blade 16 to
a direction opposite to loading. The loading element 23 is
supported in place with fastening rods 25. In the doctor apparatus
according to the invention, the loading element can move the blade
into two directions. When only one loading element is required for
the doctor apparatus instead of the previous two, the entirety can
be made simpler and easier to manufacture. The loading element can
consist of sections or it can be continuous. The operation of the
loading element can be based on pressure variation, for example, as
in a hose. Heat expansion can also be utilized in the loading
element since heat expansion is uniform and provides uniform
loading.
[0033] A doctor apparatus can be used to clean a roll or a belt,
for example, by doctoring. A doctor apparatus can also be used to
detach a web from the proximity of a belt or a roll. A doctor blade
is used to detach, for example, a paper web from a moving surface
or to keep the surface of a moving element otherwise clean by
doctoring. The moving element can be a roll or a belt, for example.
A doctor apparatus can also be used in connection with coating or
creping.
[0034] In the doctor apparatus 10 shown in FIG. 2 the loading
element 23 is a loading hose 24. With a loading hose, uniform
loading is achieved by utilizing an overpressure. The use of
overpressure is advantageous in a paper machine since it is used in
many applications and it is a very reliable solution. In addition,
pressurized air does not soil. The loading hose used for generating
the load can also consist of sections, but advantageously the
loading hose is continuous. The loading hose 24 is supported in
place with fastening rods 25. The loading hose contracts when it is
depressurized. On the other hand, the loading hose expands when it
is overpressurized. The terms `vacuum` and `overpressure` are used
to refer to the pressure level prevailing within a pipe compared to
the pressure level surrounding the pipe. The doctor apparatus
according to the invention assists in saving a remarkable amount of
work and pipe material in the machine construction as a pipe of its
own is installed for each loading hose of the doctor apparatus for
applying pressurized air for these. In the doctor apparatus
according to the invention, one loading hose can move the blade
into two directions. When only one loading hose is required for the
doctor apparatus instead of the previous two, only one pipe is also
required instead of the previous two. Thus the savings in
constructing the web forming machine are significant. The saving is
significant since doctor apparatuses in which the invention can be
utilized are typically about 20 in number in a paper machine. For
each doctor, for example, 10 mm pipe is installed for a length of
20 m. Merely the pipes made of stainless steel cost tens of
thousands, even hundreds of thousands of euros. Besides pipes, the
amount of other pneumatic components required is also smaller,
which will create savings correspondingly. Remarkable savings are
also made in the installation costs.
[0035] FIG. 3a shows the doctor apparatus 10 according to the
invention with the blade 16 contacting the roll surface 26. The
cross section of the wall 28 of the loading hose 24 used is curved
for a portion exceeding 70%, preferably for a portion exceeding
90%. Thus the loading hose has fastening profiles, for example,
over a portion smaller than 30%, preferably over a portion smaller
than 10%. In other words, the loading hose 24 is free of sharp
angles. When the surface of the loading hose 24 is curved, hose
grooves 36 in the blade holder 14 and the frame component 12 are
also curved. With the walls being curved, placing the loading hose
between the blade holder and the frame component is easier than
before. Typically the loading hose is inserted between the blade
holder and the frame component from the end. On the other hand, it
is possible to contemplate a case in which the loading hose remains
in place in the frame component and the blade holder is removed. It
is essential that removing the blade holder is easier and faster
than before. Then the blade holder can be removed for cleaning, for
example, or it can be completely replaced faster than before.
Furthermore, a curved surface does not collect dirt in a similar
way as angular shapes. Moreover, a curved surface is easier to
clean.
[0036] In the doctor apparatus 10 according to the invention shown
in FIG. 3a, the cross section of the loading hose 24 is
substantially circular. Advantageously, the cross section of the
loading hose is substantially circular at some stage of loading. A
loading hose with a circular cross section is an advantageous
embodiment from the curved shape due to easy replaceability and
good properties of keeping clean. Advantageously, the loading hose
has a silicone construction whereby it slides in place more easily
than before. A pipe with a silicone construction provided with
curved walls is easy and economical to manufacture with pultrusion
as well as extrusion. From the economical point of view it should
be noted that the manufacturing costs of a curved, mainly circular,
loading hose are only about a fifth of the price of a loading hose
with an angular shape. A loading hose with an angular shape refers
to, for example, the design of the loading hose shown in FIG. 2, in
which keeping the loading hose in place is based on the angular
basic design of the loading hose as well as on fastening rods.
[0037] The replacement of the blade holder is partially facilitated
by the fact that when the loading hose is in the depressurized
state, the blade is not loaded against the roll surface. Removing
the blade holder from the frame component is simpler than before
when there is only one loading hose and even the one loading hose
is depressurized.
[0038] FIG. 3b shows the doctor apparatus 10 according to the
invention shown in FIG. 3a with the blade 16 detached from the roll
surface 26. Thus there is a gap 38 between the blade 16 and the
roll surface 26. Between the blade holder 14 and the frame
component 12 there is a connection 34 allowing turning, and the
loading element, more precisely the loading hose 24, is on the
opposite side, relative to the blade, of the connection 34 allowing
turning in the direction parallel with the blade 16. The expression
`in the direction parallel with the blade 16` means here the
direction from the tip 31 of the blade 16 to the base 29 of the
blade. The direction parallel with the blade is indicated with a
double-headed arrow 32. In other words, the loading hose 24 is
depressurized for detaching the blade 16 from the roll surface 26.
When the blade is detached from the roll surface by means of a
vacuum, a vacuum is needed only for a small portion of the total
time. In addition, the vacuum does not need to be high for moving
the blade holder and further the blade. When doctoring with the
blade, higher forces and more long-lasting pressure are required.
Hence, the loading hose is advantageously depressurized for
detaching the blade from the roll surface and overpressurized for
loading the blade against the roll surface. An ejector uses
pressurized air of about 70 l/min for generating a vacuum,
therefore the consumption of pressurized air during the replacement
is very low.
[0039] In the doctor apparatus 10 shown in FIGS. 3a and 3b, the
loading hose 24 includes opposite fastening profiles 30 for tying
both the frame component 12 and the blade holder 14 to the same
loading hose 24. With opposite fastening profiles, forces provided
by the vacuum of the loading hose during contraction are conveyed
to the frame component and the blade holder. In addition, the
fastening profiles keep the loading hose with mainly curved walls
in place also upon the overpressurization of the loading hose.
Advantageously, there are two fastening profiles. Thus the loading
hose can be kept securely in place conveying the forces as desired.
On the other hand, the loading hose lacks unnecessary fastening
profiles, which would unnecessarily complicate the installation of
the loading hose. Moreover, each fastening profile produces costs
in the manufacturing stage.
[0040] In the doctor apparatus 10 according to the invention shown
in FIG. 3a, there is a connection 34 allowing turning between the
blade holder 14 and the frame component 12. The loading hose 24 is
located in hose grooves 36 provided in the blade holder 14 and the
frame component 12. The hose grooves 36 are provided with counter
profiles 48 for the fastening profiles 30. In addition, the
fastening profiles 30 are on the opposite side of the diameter d of
the loading hose 24 relative to the connection 34 allowing turning
between the blade holder 14 and the frame component 12. The
diameter d of the loading hose 24 is at the right angle relative to
the longitudinal direction of the blade 16. When the fastening
profiles are on the other side of the loading hose diameter than
the connection allowing turning, the movement of the loading hose
can be efficiently transferred to the movement of the blade
holder.
[0041] In the doctor apparatus 10 shown in FIG. 3a, the gap 38
between the blade 16 and the roll surface 26 is formed between the
roll surface 26 and the tip 31 of the blade 16. Although the tip 31
is in contact with the roll surface, it is possible to talk about a
gap between the blade and the roll surface. When the blade contacts
the roll surface while adjusting the gap between the blade and the
roll surface, the force of the blade loading the roll surface is
adjusted. The blade 16 is fastened to the blade holder 14, which is
further supported to the frame component 12. In addition, the
loading hose 24 is located between the blade holder 14 and the
frame component 12 in such a way that the distance between the
blade holder 14 and the frame component 12 decreases at the loading
hose when depressurizing the loading hose 24. Correspondingly, the
distance a between the blade holder 14 and the frame component 12
decreases on the side of the loading hose 24 of the connection 34.
The connection 34 allows turning of the blade holder 14 relative to
the frame component 12. As the blade holder 14 turns relative to
the frame component 12 upon the depressurization of the loading
hose 24, the blade 16 detaches from the roll surface 26.
[0042] In the doctor apparatus 10 shown in FIG. 3a, the distance a
between the blade holder 14 and the frame component 12 increases
when the loading hose is overpressurized. Certainly, as the blade
16 encounters the roll surface 26, the blade holder 14 cannot turn
more, whereby the distance a does not increase any more remarkably.
As the blade 16 and the presser plate 18 bend, the distance a
increases slightly. Then the force produced by the overpressurized
loading hose 24 is directed as a load to the gap 38 between the
blade and the roll surface.
[0043] In the doctor apparatus 10 according to the invention shown
in FIG. 3a, the angle .alpha. between the opposite fastening
profiles 30 is 40-140.degree.. Thus the position of the fastening
profiles enables good movability together with strong
constructions. By strong constructions is meant here that the
counter profile of the fastening profile does not come too close to
the edge of the construction in the blade holder or in the frame
component. Advantageously, the angle .alpha. is 70-110.degree. in
order that ample movability is achieved with strong
constructions.
[0044] In the doctor apparatus 10 shown in FIG. 3a, the fastening
profiles 30 are protruding from the loading hose 24. Then the
counter profiles 48 of the fastening profiles 30 are inside the
frame component 12 and the blade holder 14. Thus it is possible to
manufacture a loading hose 24 which is thin but still resistant.
When the loading hose is mainly thin, the loading hose contracts
even at a low vacuum. The blade holder and the frame component, on
the other hand, can be made more resistant as they are free of
projections.
[0045] FIG. 4 shows the blade holder 14 according to the invention.
The blade holder is used in a doctor apparatus in a web forming
machine for doctoring a moving surface. The blade holder 14
includes a loading element groove 35. In addition, the blade holder
14 includes only one loading element groove 35 adapted to
bidirectional loading. The blade holder 14 is adapted to be
connected to a frame component 12 in such a way that a loading
element 23 (FIG. 3a) is adapted between the blade holder 14 and the
frame component 12 in the loading element groove 35. A blade holder
comprising only one loading element groove is used in a doctoring
apparatus provided with one loading hose. Such a doctoring
apparatus is economically more advantageous to install as described
above. A blade holder comprising only one hose groove is also
easier to mount in place than before.
[0046] The blade holder shown in FIG. 4 includes profiles 33 for
fastening the loading element 23 (FIG. 3a). Furthermore, the
profiles 33 for fastening the loading element 23 consist of one
loading element groove 35. in other words, the profiles 33 with
which the loading element is fastened to the blade holder form
together one loading element groove 35. Such a blade holder
comprises only one loading element groove.
[0047] The blade holder 14 according to the invention shown in FIG.
4 has a blade groove 40. The blade 16 (FIG. 3a) is adapted to be
fastened to the blade groove 40.
[0048] The blade holder 14 has a connection component 44 allowing
turning for fastening the blade holder 14 to the frame component 12
(FIG. 3a). Correspondingly, the frame component 12 is provided with
a connection component 46 for fastening the blade holder 14 to the
frame component 12 (FIG. 3a). The connection components 44, 46 form
a connection 34 allowing turning. In addition, the loading element
groove 35 is on the opposite side of the connection component 44,
relative to the blade groove 40, in the direction parallel with the
blade groove 40. The expression "direction parallel with the blade
groove" refers to the direction which is congruent with the blade
direction. The direction of the blade 16 is indicated with the
double-headed arrow 32 in FIGS. 3a and 3b. The direction of the
blade groove 40, in turn, is indicated with the double-headed arrow
42 in FIG. 4.
[0049] In the blade holder 14 shown in FIG. 4, the loading element
groove 35 is a hose groove 36. In this case, a hose providing
uniform loading is used as the loading element. In the blade holder
14, the hose groove 36 has an edge 50 on the side of the connection
component 44 and an outer edge 52. Advantageously, the counter
profile 48 is closer to the outer edge 52 than to the edge 50 on
the side of the connection component 44.
[0050] In the blade holder shown in FIG. 4 the loading element
groove 35 includes a counter profile 48 and a loading element
profile 37. The force applied during doctoring is conveyed to the
blade holder via the loading element profile. A force affecting in
another direction is conveyed to the blade holder, in turn, via the
counter profile. In other words, the counter profile keeps the
loading element in place when contracting the loading element.
[0051] FIG. 5a illustrates a doctor apparatus 10' according to
prior art in the closed position. Correspondingly, FIG. 5b shows
the doctor apparatus 10 according to the invention in the closed
position. In the closed position, a surface is doctored with the
blade of a doctor apparatus. In other words, the blade included in
the doctor apparatus is loaded against the surface. In the closed
position, the loading element 19, 19' included in the doctor
apparatus is in an extreme position as large as possible. In FIG.
5c, FIGS. 5a and 5b are shown placed on top of each other such that
the differences between the application according to prior art and
the application according to the invention in the closed position
are revealed in the same figure.
[0052] In the doctor apparatus 10 according to prior art shown in
FIG. 5a, the angle .beta. between the outer surface 54 of the blade
holder 14 and the outer surface 56 of the frame component 12 is
6.degree.. The distance b between the rear profile 58 of the blade
holder 14 and the rear profile 60 of the frame component 12 is 16
mm.
[0053] In the doctor apparatus 10 according to the invention shown
in FIG. 5b, the angle .alpha. between the outer surface 54 of the
blade holder 14 and the outer surface 56 of the frame component 12
is 9.degree.. Angles .alpha. and .beta. have been measured in such
a way that the outer surface of the frame component forms a side of
the angle and the angle is given as a positive value clockwise from
this side. The distance a between the rear profile 58 of the blade
holder 14 and the rear profile 60 of the frame component 12 is 21
mm.
[0054] FIG. 5c reveals that the distance a in the doctor apparatus
according to the invention is greater than the corresponding
distance b in the doctor apparatus according to prior art.
[0055] The full or overpressurized loading hose 24 of the doctor
apparatus 10 shown in FIG. 5b includes a first wall portion 62,
which is outwardly curved, a second wall portion 64, which is
outwardly curved, and a third wall portion 66, which is outwardly
curved. The wall portions 62, 64 and 66 are advantageously mutually
substantially of the same size. The wall portions being
substantially of the same size, each of them covers 90-150.degree.,
advantageously 105-135.degree., of the diameter of the loading hose
24. When the wall portions themselves are curved, the cross section
of the loading hose is substantially circular. In other words, a
small deviation from a circular shape may exist between the curved
wall portions but as the deviation is small, the cross section has
a substantially circular shape.
[0056] FIG. 6a illustrates a doctor apparatus 10' according to
prior art in the neutral position. FIG. 6b shows the doctor
apparatus 10 according to the invention correspondingly in the
neutral position. In the neutral position, a surface is no more
doctored with the blade of a doctor apparatus. The blade is
typically detached from the surface to be doctored, but the blade
can still contact the surface to be doctored. If the blade contacts
the surface, the contact is light and not suitable for doctoring.
In the doctor apparatus 10' according to prior art, the loading
element 19' is then contracted almost to the extreme position. In
the doctor apparatus 10 according to the invention, the loading
element 19 is slightly contracted. In FIG. 6c, FIGS. 6a and 6b are
shown placed on top of each other such that the differences between
the application according to prior art and the application
according to the invention in the neutral position are revealed in
the same figure.
[0057] In the doctor apparatus 10' according to prior art shown in
FIG. 6a, the angle .beta.' between the outer surface 54 of the
blade holder 14 and the outer surface 56 of the frame component 12
is 5.degree., therefore the explementary angle .beta. is
355.degree.. The distance b between the rear profile 58 of the
blade holder 14 and the rear profile 60 of the frame component 12
is 7 mm. Compared to the closed position, the angle between the
frame component and the blade holder has decreased by 11.degree.
and the distance b by 9 mm.
[0058] In the doctor apparatus 10 according to the invention shown
in FIG. 6b, the angle .alpha.' between the outer surface 54 of the
blade holder 14 and the outer surface 56 of the frame component 12
is 2.degree., therefore the explementary angle .alpha. is
358.degree.. The distance a between the rear profile 58 of the
blade holder 14 and the rear profile 60 of the frame component 12
is 12 mm. Compared to the closed position, the angle between the
blade holder and the frame component has decreased by 11.degree.
and the distance b by 9 mm.
[0059] FIG. 6c reveals that in the doctor apparatus according to
the invention, remarkable turning of the blade holder relative to
the frame component is possible. In turn, in the doctor apparatus
according to prior art, the blade holder can no more move a lot
relative to the frame component.
[0060] In the doctor apparatus 10 shown in FIG. 6b, the loading
hose 24 is a circuit formed by a first wall portion 62, a second
wall portion 64, a third wall portion 66, and a fourth wall portion
68. The third wall portion is included in the circuit between the
first wall portion and the second wall portion. Correspondingly,
the fourth wall portion is included in the circuit between the
first wall portion and the second wall portion. The fourth wall
portion 68 included in the loading hose 24 is on the side of the
connection component 46. The third wall portion 66, in turn, is on
the opposite side of the loading hose 24 relative to the connection
component 46. The fourth wall portion functions as a hinge element
when depressurizing the loading hose.
[0061] In FIG. 6b, the first wall portion 62 is in connection with
the frame component 12 and the second wall portion 64 is in
connection with the blade holder 14. The fastening profiles 30
define the fourth wall portion 66, which is in the loading hose
circuit between the first wall portion 62 and the second wall
portion 64. In the neutral position and in the open position (FIG.
7b) the third wall portion 66 is detached from the blade holder 14
and the frame component 12. The fourth wall portion 68 of the
loading hose 24 located on the side of the connection component 46
is detached from the blade holder 14 and the frame component 12
when in the closed position (FIG. 5b) and, over a partial distance,
when in the neutral position and in the open position as well (FIG.
7b).
[0062] In the doctor apparatus 10 shown in FIG. 6b the inner
surface 63 of the first wall portion 62 and the inner surface 65 of
the second wall portion 64 of the loading hose are concave in the
overpressurized and depressurized states as seen from inside of the
loading hose. Advantageously, the inner surface 69 of the fourth
wall portion 68 is also concave in both the overpressurized and
depressurized states. In addition, the inner surface 67 of the
third wall portion 66 is concave in the overpressurized state (FIG.
5b) and convex in the neutral position as well as in the
depressurized state (FIG. 7b).
[0063] In the doctor apparatus 10 shown in FIG. 6b, the inner
surface 67 of the o third wall portion 66 of the loading hose 24 is
convex in the depressurized state. In the doctor apparatus 10 shown
in FIG. 5b, in turn, the inner surface 67 of the third wall portion
66 of the loading hose 24 is concave in the overpressurized state.
This is as seen from inside of the loading hose.
[0064] In the doctor apparatus 10 shown in FIG. 6b, the loading
hose 24 includes a first wall portion 62, a second wall portion 64
and a third wall portion 66, and there are provided fastening
profiles 30 on both sides of the third wall portion 66. Thus the
loading hose 24 can be connected to the frame component 12 along
the first wall portion 62 and connected to the blade holder along
the second wall portion 64. Thus the hose does not move
substantially along its first wall portion relative to the blade
holder. Correspondingly, the hose does not move substantially along
the second wall portion relative to the frame component.
[0065] FIG. 7a illustrates a doctor apparatus 10 according to prior
art in the open position. FIG. 7b shows the doctor apparatus 10
according to the invention correspondingly in the open position. In
the open position, a surface is not doctored with the blade of a
doctor apparatus. The blade is detached from the surface to be
doctored. Thus the blade can be removed from the doctor apparatus.
In the doctor apparatus 10' according to prior art, the loading
element 19' is then fully contracted to the extreme position.
Correspondingly, the opening hose 22' has filled up for detaching
the blade from the surface to be doctored. Correspondingly, in the
doctor apparatus 10 according to the invention, the loading element
is contracted to the extreme position. In FIG. 7c, FIGS. 7a and 7b
are shown placed on top of each other such that the differences
between the application according to prior art and the application
according to the invention in the open position are revealed in the
same figure.
[0066] In the doctor apparatus 10' according to prior art shown in
FIG. 7a, the angle .beta.' between the outer surface 54 of the
blade holder 14 and the outer surface 56 of the frame component 12
is 8.degree., i.e. the explementary angle .beta. is 352.degree..
The distance b between the rear profile 58 of the blade holder 14
and the rear profile 60 of the frame component 12 is 4.7 mm.
Compared to the closed position, the angle between the blade holder
and the frame component has decreased by 14.degree. and the
distance b by 11.3 mm.
[0067] In the doctor apparatus 10 according to the invention shown
in FIG. 7b, the angle .alpha.' between the outer surface 54 of the
blade holder 14 and the outer surface 56 of the frame component 12
is 12.degree. and the explementary angle .alpha. is 348.degree..
The distance a between the rear profile 58 of the blade holder 14
and the rear profile 60 of the frame component 12 is 3 mm. Compared
to the closed position, the angle between the blade holder and the
frame component has decreased by 21.degree. and the distance b by
18 mm.
[0068] FIG. 7c reveals that in the doctor apparatus according to
the invention the blade holder has turned more relative to the
frame component than in the doctor apparatus according to prior
art. Compared to the closed position, the angle between the blade
holder and the frame component has decreased 7.degree. more in the
blade holder according to the invention than in the blade holder
according to prior art. The gap c indicates how much more the blade
of the doctor apparatus according to the invention has turned
compared to the blade of the doctor apparatus according to prior
art. The gap c is 16 mm whereby removing the blade from the doctor
apparatus according to the invention is easier than before.
[0069] In the doctor apparatus 10 shown in FIG. 7b, the
depressurized loading hose 24 includes a first wall portion 62 on
the inner surface 63, a second wall portion 64 on the inner surface
65, and a third wall portion 66, which is between the inner surface
63 of the first wall portion 62 and the inner surface 65 of the
second wall portion 64. The third wall portion being located
between the inner surface of the first wall portion and the inner
surface of the second wall portion, the third wall portion is
located in the area defined together by the first wall portion and
the second wall portion. When the third wall portion is bent
between the first and the second wall portions, the loading hose
can be made very small. On the other hand, the loading hose is
large when pressurized. Such a design enables greater deformations
than before for the loading hose. Then the blade movement relative
to the surface to be doctored is greater than before.
Advantageously, the first wall portion and the second wall portion
are curved. A curved shape assists in putting the loading hose in
place, prevents soiling and enables a hose groove with an
advantageous stress distribution.
* * * * *